CHM Decoder is described as 'may decompile your CHM file (Compiled Windows HTML Help) or e-book and extract all source files. This tool free for use and work easily and quickly. Want to convert CHM to HTML and view that in your PocketPC or in your web pages? CHM Decoder can help to you'. There are more than 25 alternatives to CHM Decoder for a variety of platforms, including Windows, Linux, Mac, PortableApps.com and Google Drive. The best alternative is Okular, which is both free and Open Source. Other great apps like CHM Decoder are 7-Zip ZS (Free, Open Source), xchm (Free, Open Source), Explzh for Windows (Free Personal) and HelpNDoc (Free Personal).
xCHM is a cross-platform GUI front-end to chmlib, with borrowed bits from Pabs' chmdeco project. Originally written for UNIX systems (Linux, *BSD, Solaris), xCHM has been since ported to Mac OS X and Windows.
Explzh for Windows is a file operation tool created with the concept of treating archive files, CD-ROM virtual disk images (ISO-9660 / ISO-13346), and FTP hosts as virtual folders and handling them like an explorer.
Kchmviewer is a free, open-source CHM (MS HTML help) and EPUB viewer written in C++ for Unix, Mac and Windows systems. Unlike most existing CHM viewers for Unix, it uses Trolltech Qt widget library, and could optionally be compiled for better KDE integration.
Vole Media CHM Free Edition lets you create standard and edit CHM with ease. Since CHM is totally supported by Microsoft Windows. Readers don’t need install any software can open and read CHM file. This software is 100% Portable.
WinCHM - Help authoring software (CHM,WebHelp,Single HTML - Word, PDF) WinCHM is a very easy-to-use help authoring tool. Not needing to learn too much, you can be master of creating HTML help(CHM), Web help, PDF manual and Word documents.